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Abstract: The simultaneous ultrasonic and microwave assisted extraction (UMAE) technique was first employed to obtain phenolics. The effects of UMAE variables including extraction time, microwave power, and solvent to solid radio on the yield of phenolics were investigated. The optimized conditions were as follows: solvent to solid ratio was 20:1 (ml/g), extraction time was 30s, microwave power was 500W and two times of extraction. Moreover, the phenolic yield of UMAE was higher than that by maceration, indicating a significant reduction of extraction time and an improvement of efficiency. The phenomenon is related to the strong disruption of leaf tissue structure by microwave induced expansion and ultrasonic shaking, which had been observed with the scanning electron microscopy. The phenolic compositions of the extract was then identified by ultra performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS), 10 compounds had been characterized, providing a more complete identification of phenolic compounds in burdock leaves than previously reported. The occurrence of benzoic acid and p-coumaric acid is reported for the first time. This study suggests that UMAE is a good alternative for the extraction of phenolics, with a great potential for industrial application. Also, UMAE provides a new sample preparation technique for characterization of the phenolic compounds from plants. [Copyright &y& Elsevier]

Abstract: The simultaneous ultrasonic/microwave assisted extraction (UMAE) of inulin and production of phenols-rich dietary fibre powder from burdock root was studied. It was found that UMAE required a much shorter extraction time than conventional stirring extraction. And the recovery of inulin increased with the increase of microwave power as well as solvent to solid ratio. A comparison of scanning electron microscopy images of raw and simultaneous ultrasonic/microwave treated burdock root indicated microfractures and disruption of cell walls in burdock root flakes. The dietary fibre powder prepared from the residue of burdock root after inulin extraction was rich in phenols (302.62mg GAE/100g powder). The results showed that drying temperature in the selected range did not significantly affect the hydration properties. The relatively high water retention capacity, swelling capacity and oil-holding capacity of the dietary fibre powder indicated its broad use as a modifier of properties of formulated products. [Copyright &y& Elsevier]

Abstract: Enrichment of burdock leaf components and the inhibition effect of the obtained 7 burdock leaf fractions on formation of biofilm have been evaluated for the first time. Firstly, burdock leaf fractions were obtained though separation of burdock leaf extracts by macroporous resin column chromatography, and four fractions were obtained, namely, water elution fraction, 20%, 34% and 70% ethanol eluted fractions. It was found that the 20% and 34% ethanol fractions both significantly inhibited the formation of biofilm by Escherichia coli, with IC50 of 1.10 and 1.01 mg/ml, respectively. The 70% ethanol elution fraction exhibited the strongest inhibitory activity against biofilm formation with an IC50 of 0.017 mg/ml. In order to obtain more fractions with higher inhibitory activity, polyamide resin was used to further purify the 34% ethanol elution fraction. The second chromatography separation significant improved the activity of burdock leaf fractions and the IC50 of a new fraction was 0.03 mg/ml. The phenolic contents of the fractions ranged from 7.5 to 369.7 mg/g and there was a high correlation between the anti-biofilm capacity and phenolic contents, except for 70% ethanol fraction. Scanning electron microscopy (SEM) observation showed that there was no biofilm formation for cultures treated with burdock leaf fraction, conforming the significant inhibition activity of burdock leaf fraction against the formation of biofilm. The results suggest that separation and enrichment of the active ingredients could significantly improve the activities of fractions and the obtained burdock leaf fractions provide new alternatives for control of biofilms. [Copyright &y& Elsevier]